Phloretin enhances adipocyte differentiation and adiponectin expression in 3T3-L1 cells

Adipocyte dysfunction is strongly associated with the development of cardiovascular risk factors and diabetes. It is accepted that the regulation of adipogenesis or adipokines expression, notably adiponectin, is able to prevent these disorders. In this report, we show that phloretin, a dietary flavonoid, enhances 3T3-L1 adipocyte differentiation as evidenced by increased triglyceride accumulation and GPDH activity. At a molecular level, mRNA expression levels of both PPAR gamma and C/EBP alpha, the master adipogenic transcription factors, are markedly increased by phloretin. Moreover, mRNA levels of PPAR gamma target genes such as LPL, aP2, CD36 and LXR alpha are up-regulated by phloretin. We also show that phloretin enhances the expression and secretion of adiponectin. Co-transfection studies suggest the induction of PPAR-gamma transcriptional activity as a possible mechanism underlying the phloretin-mediated effects. Taken together, these results suggest that phloretin may be beneficial for reducing insulin resistance through its potency to regulate adipocyte differentiation and function. (C) 2007 Elsevier Inc. All rights reserved.